Strain responsive apparatus



April E. E. SIMMONS,IJR 2,316,203

STRAIN RESPONSIVE APPARATUS Original Filed Feb. 25, 1940 INVENTQR EDWARDESFMMOIEfi JR.

ATTQRN EY Patented Apr. 13, 1943 STRAIN RESPONSIVE APPARATUS Edward E.Simmons, In, Pasadena, Calif.

Original application February 23, 1940, Serial No.

320,327, now Patent No. 2,292,549, dated August 11, 1942.

Divided and this application July 1, 1942, Serial No. 449,297

} 3 Claims. This invention relates generally to strain responsiveapparatus and more particularly to an improved dynamometer. Thisapplication is a division of my copending application Serial No.320,327, filed February 23, 1940, now Patent No. 2,292,549, issued Aug.11, 1942.

It is an object of my invention to provide an improved dynamometer thatis relatively simple and economical in construction, operation andmaintenance as well as being compact and rugged combined with a highdegree of sensitivity, accuracy and reliability. The term dynamometer asused herein broadly refers to the combination of a member to which aforce is applied and means responsive to the strain imposed in saidmember as a result of the applied force.

Other objects and advantages will be more apparent to those skilled inthe art from the following description of the accompanying drawing whichis a side elevation of my improved dynamometer.

My improved dynamometer consists of a cotton insulated strand orfilament l of continuous solid electrical conducting material cementedthroughout its effective length to a flat piece of flexible steel 2.This device may be calibrated by bending the flexible steel with a givenforce and notin the change in electrical resistance of the filament I,this change in resistance being in response to a given strain ordeformation of the flexible piece ,2. This flexible piece is preferablyin the form of a cantilever anchored at its fixed end to a rigid member3 while its outer end is free. The filament is connected to any suitablemeasuring circuit such as a Wheatstone bridge to form one arm of thebridge thereby to measure the change of resistance of the filament inaccordance with unbalance of the bridge caused by flexure of thecantilever. The material of which the filament is made. its diameter andthe cementing or bonding mtaerial are all described in my said copendingoriginal application, as well as the probable theory on which thefilament operates under the influence of being firmly bonded throughoutits 7 effective length. Therefore, it is not deemed necessary todescribe such materials or characteristics in this present application.All other characteristics and qualities incident to the presentinvention and described in said copending application are likewise to beconsidered as embodied in my present disclosure.

From the foregoing disclosure, it is seen that the dynamometer disclosedherein provides an extremely simple, direct, rugged and compact meansfor measuring the force applied to the cantilever beam and thesequalities are combined with a high degree of sensitivity, accuracy,freedom from hysteresis and ability to reproduce its results faithfully.

It will of course be understood that various changes in details ofconstruction and arrangement of parts may be made by those skilled inthe art without departing from the spirit of the invention as set forthin the appended claims.

I claim:

1. A bending element having a continuous solid filament of materialwhose electrical resistance varies in accordance with its strain bondedthroughout its effective length to said element to produce a variableresistance upon bending of said element.

2. A dynamometer comprising a flexible cantilever member normally fixedat one end and adapted to have free movement at its other end, and acontinuous solid filament of material whose electrical resistance variesin accordance with its strain bonded throughout its eflective length toasid member, whereby flexure of said member upon application of force toits free end varies the strain in said member and accordingly changesthe electrical resistance of said filament.

3. The combination set forth in claim 2 further characterized in thatsaid filament i's'bonded throughout its effective length to the surfaceof said member in a direction lengthwise thereof.

EDWARD E. SIMZMONS, J I.

